C program to perform arithmetic operations in menu driven approach

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
void main()
{
	int ch;
	float a,b;
	while(1)
	{
		printf("Menu \n");
		printf("1.Addition\n");
		printf("2.Subtraction\n");
		printf("3.Multiplication\n");
		printf("4.Division\n");
		printf("5.Exit\n");
		
		printf("Enter your choice :");
		scanf("%d",&ch);
		
		if((ch>=1) && (ch<=4))
		{
			printf("Enter two numbers : ");
			scanf("%f%f",&a,&b);
		}
		
		switch(ch)
		{
			case 1 : 	printf("Res : %f\n",a+b);
						break;
			
			case 2 : 	printf("Res : %f\n",a-b);
						break;
			
			case 3 : 	printf("Res : %f\n",a*b);
						break;
			
			case 4 : 	printf("Res : %f\n",a/b);
						break;
			
			case 5 : 	exit(1);
			default: 	printf("Wrong choice\n");
		}
	}
}